The MiscDotGeek uBITX FAQ

The uBITX FAQ

The uBITX is out and folks have a lot of questions about the kit. It’s my intention to answer as many of them as possible. Note: Questions about building the uBITX, what skills are needed, and suitability for beginners are all answered in the BITX40 FAQ.

How much does the uBITX cost, and where can I order one?

Photo Credit: Ashhar Farhan

The uBITX went on sale on 12/9/2017 for $109. After the holidays it’ll be $129.You can purchase the uBITX at the official site, http://hfsignals.com.

Farhan’s goal has been to make high quality equipment available at a low price, as evidenced by the BITX40 only costing $59. The uBITX is equally affordable, while costing more than the BITX40 due to its higher parts count and more extensive labor required to build and tune the board.

How do you pronounce “uBITX”?

From the words of Ashhar Farhan, the creator of the uBITX himself: “I pronounce it as ‘micro bitx’, you can choose your own.” We all type “uBITX” but it’s not a “U” it is the symbol for “micro” which is µ, so it is technically the µBITX. Nobody has that key on their keyboard, however, and it’s not straightforward to type. This leads us to using “uBITX” and the pronunciation that often follows, “you bit ex”. As long as someone else knows what you’re talking about, any pronunciation will work 😉

How is the uBITX different from the BITX40?

The uBITX has a lot in common with the BITX40. It is the next step in the evolution of the BITX40 design and has some significant technological differences, and many added features. Let’s look at a few of the differences between the BITX40 and the uBITX:

Multi-Band

First and foremost, the uBITX is a multi band radio, and needs no modification to be active on all HF bands except 160m. That means you can use the uBITX on 80m, 60m, 40m, 30m, 20m, 17m, 15m, 12m, and 10m!

CW

Another wonderful feature is that the radio has not just SSB, but also CW! One needs only to connect a keyer.

Raduino Differences

The Raduino is used but with a different program and slightly different hardware. The SIS5351 DDS chip has three outputs. The BITX40 uses only one output for the VFO. The uBITX makes use of all three. Instead of providing only the VFO it also provides the BFO. The Raduino is also responsible for providing the CW tone when the CW keyer is used.

The Raduino plugs directly into the uBITX board, rather than with wires to the main board such as in the BITX40. The uBITX and the Raduino can be separated, as long as coax cable is used to connect the signal wires to the main board.

Power Amplifier and Output

The inexpensive IRF510 is still used. Instead of a single IRF510, there are two of them configured in a “push-pull” configuration. This is done in order to produce a cleaner output, eliminating the need for a Low Pass Filter on every band. This is why you see 4 sets of filters, but 9 bands are supported. As a result there are two heat sinks.

The PA produces 10W on lower bands, but the output decreases on higher bands. The lowest output is 5W on 28mhz (10m).

How big is the uBITX?

The board itself is 6″x5.5″, with the heat sinks for the dual IRF510’s extending past the rear of the board. The Raduino protrudes half an inch from the front of the main board.

What are the extra resistors for?

The uBITX includes a 2.2k ohm and a 10k ohm resistor. They are for CW paddle. The 2.2k resistor goes between the CW input and the the Dot paddle, and the 10k between CW input and the Dash paddle.

Where can I get help with the uBITX?

Support for the uBITX is almost entirely community based. There are two popular communities. The first is the BITX20 mailing group, which can be used fully via the web, at Groups.io. The link is here:

Arthur Bryant

Hi Arthur, No I don’t think it would be a good fit. It could be made to work, I’m certain, but I don’t think it would keep the radio fully featured as designed. The uBITX Raduino is very specific to the uBITX, but the QRP Labs VFO is just a VFO, with no BFO or CW tone output.